first question :which xorg version is installed ? i thought it was 7.x and see in log 1.3 ? how to be sure to install and use version 7 ?

second question :i'm not sure about the name of the two screens (0 and 1) : it looks like there is a confusion between them (in my mind maybe).but i see mga(0) default mode 1440x900 and mga(1) default mode '1920x1080' ? Is it not the opposite on xorg.conf ?

third and last question :what I made wrong or forgotten ?

If you need more information from error log, ask me, i don't send the entire file that's too big ...